The present invention relates to electrical connectors in general, and more particularly to electrical connectors used to interconnect a display device such as a liquid crystal display (xe2x80x9cLCDxe2x80x9d or xe2x80x9cLCD""sxe2x80x9d) to a circuit board, in a stacked configuration.
Prior art methods and devices are known for interconnecting electronic assemblies. Such methods and devices are used to connect relatively small components to adjacent electronic components, such as circuit boards. A significant problem with conventional methods and devices for interconnecting LCD""s to their respective associated electronic components is the limited space afforded for such connections and assembled components.
To reduce the overall size of the end product, it is desirable to vertically xe2x80x9cstackxe2x80x9d such components when possible. LCD""s may be arranged in a vertically stacked arrangement. LCD""s often are provided in association with a lightguide device that is incorporated into the stack and adapted for distributing light around the periphery of an LCD. A typical LCD assembly mounted upon a cellular telephone, for example, includes an upper display portion and a lower circuit board portion. Sandwiched between the LCD and the circuit board is the optical lightguide. Occasionally, a connector is provided between the LCD and circuit board (i.e. adjacent the lightguide device).
Historically, LCD""s have employed connections which appear on the underside of the display, with a semiconductor chip located away from the display, such as on the circuit board itself. However, modern assemblies sometimes include a mounted semiconductor chip on the glass of the upper display. A chip mounted on the glass of the upper display is helpful in some instances because it reduces the overall number of contact pads that must be provided on the lower surface of the LCD, due to the lesser number of communications that must be made external to the LCD in that instance.
Connectors designed to interconnect an LCD with a circuit board typically have been comprised of elastomeric or foam material that springs back when compressed. For example, U.S. Pat. No. 5,709,576 to Lippmann discloses an elastomeric connector that couples terminal pads of an LCD with corresponding terminal pads of a printed wiring board. Sense pads are located on the terminal strips and arranged so that a continuity test on substantially opposed contact pads will verify pad alignment. In some applications, the tendency of such elastomeric materials to resume their original shape after deformation is relied upon as a means to hold contacts in close association within the sandwich structure.
Elastomeric connectors may feature solderless contacts that connect the electrical contact pads on the LCD display with those on the printed circuit board. However, such elastomers sometimes lose their elasticity. Sometimes, electrical connection becomes faulty in such LCD""s after a period of time. Elastomeric materials of this type may comprise rubbery or foamed materials that lose some of their elasticity due to age, heat, or a combination of age and heat. When a loss of elasticity occurs, the electrical connection, which depends upon such elasticity to hold contacts in resilient communication with each other, may become faulty. Slight movement of the elastomeric connector at high temperatures or in the presence of vibration may cause undesirable conductivity problems.
It is quite often difficult to solder or connect terminals or connectors between adjacent components without bridging adjacent terminals with solder. Also, it is difficult to maintain and ensure the correct relative position (sometimes called xe2x80x9cregistrationxe2x80x9d) between the components during the manufacturing process and in subsequent use of the end product.
What is needed in the industry is a connector that is capable of integration with a lightguide in a reliable and compact arrangement. A display which is provided in a reliable connector and lightguide system that facilitates long term and reliable use of display devices at elevated heat and vibrational conditions would be very desirable. A system that facilitates reliable registration of electrical contacts during manufacture and use is needed.
In the invention, an electrical connector for interconnecting a display (such as an LCD) to a circuit board is provided in a stacked configuration. The connector comprises an insulating body, the body being comprised of a material that is capable of providing light to illuminate the display. In some applications, this light emitting structure is called a xe2x80x9clightguidexe2x80x9d. Furthermore, a leg member is provided as part of the connector. The leg member is disposed on the insulating body, and includes an outer surface that is configured for disposition adjacent to a circuit board to which the display has been electronically connected. Furthermore, at least one connector element is configured with the insulating body.
In one embodiment of the invention, the connector element may comprise a first contact foot that extends beyond the outer surface of the leg member, to enable electrical communication with the liquid crystal display. Furthermore, a second contact foot extends beyond the outer surface of the leg member for electrical communication with a circuit board. In this embodiment, the connector is positioned for registration of the connector elements with electrical contacts that are located on the display and the circuit board.
In one embodiment of the invention, the connector element includes a xe2x80x9cU-shapedxe2x80x9d member with a first end and a second end, wherein the U-shaped member has an arm portion with contact feet defined on the first end and contact feet defined on the second end. The connector element also comprises a closed-end that wraps around and fits upon the leg member configured in the body.
In another embodiment of the invention, the connector includes an opening that is provided in the body itself. Furthermore, the leg member includes a plurality of connector elements that are aligned and separated from the body. The opening in the body is located at least partially between the leg member and the body. During manufacturing operations, connector elements provided on a carrier strip are aligned over the leg member of the body, and then crimped down upon the leg member. The carrier strip portion is knocked out of the opening (or space) within the body that is adjacent to the leg member, leaving an opening.
At least one embodiment of the invention includes connector elements that comprise strip members which are bent into a closed-end and oppositely facing arms configuration. The contact feet are defined on the arms, and at least one of the arms is adapted for applying a resilient force to electrical contacts of the LCD.
Additional objects and advantages of the invention will be set forth in part in the following description, or may be obvious from the description, or may be learned through practice of the invention. The invention will be described in greater detail below through preferred embodiments as illustrated in the attached Figures.